Posts Tagged ‘overdrive’

In some of the articles, I made statements regarding a possibility of mild power amp drive, because I had not had time to really dig into the power amp to confirm or deny it, and due to the sound of Modern mode. The power amp does not overdrive. If you come across anything relating to this, any descriptions should be discarded if they contradict the following paragraphs.

Modern has some distortion present, but it isn’t clipping distortion; It’s regular ol’ harmonic distortion, which is otherwise known as “the tube sound”. I don’t have time or energy to get into it, but the power amp is designed to stay as clean as possible, but tubes do not always amplify in a “linear” way. This adds curvature to the sound waves, distorting them by bending (coloring the sound). (more…)

We’ve looked at the input and Clean, the voicing and Gain control, and V2. Now, it is time to examine V3, the coupled cathode follower. I urge you to read about cathode followers if you do not understand how they work and wish to learn more.

The biggest things for a novice to know are:

A cathode follower is usually used to lower impedance to drive a tone stack or an effects loop.

The cathode of the second tube follows the voltage on its grid closely (hence “cathode follower”).

The first tube provides amplification of the signal and stability to the cathode follower.

When coupled (wired together), the two tubes act like one (mostly). (more…)

So far, we’ve looked at the input stage and Clean mode, and the voicing and Gain controls for Channels 2 and 3. When we left off, the signal had been filtered, dropped down, filtered again, and was exiting the Gain pot by way of a 475 k grid resistor into Stage 2 (V2a).

Grid Resistor

Aside from controlling incoming current, the grid resistor serves to adjust the highest frequency allowed to enter the amplification stage by creating a filter due to the tube’s internal capacitance (around 1.6 pf). Additionally, this stage has a 20 pf capacitor in parallel to the tube. This increases the total capacitance to 21.6 pf. (more…)